The gaudy baroque facade of the Església del Monti-Sion was converted from a Gothic synagogue. It got a serious baroque makeover, inside and out, in the 16th to 17th centuries, and is now considered one of the high points of the style on the island. Gothic giveaways include the ogive arches in front of the chapels, the key vaulting in the ceiling and the long, low Catalan Gothic arch just inside the entrance.
As you wander in, a priest sitting in a booth by the entry may flip a switch and light up the curves-and-swirls baroque retablo (altarpiece) at the back of the church.